The insertion of various types of heating elements into garments is well known. Typically, this is done for items such as socks, boots, gloves, ear muffs, etc., which are used in extreme cold weather situations, Similarly, heating devices are used in various types of emergency home first aid situations.
Although the insertion of heating elements into garments has been known for an extended period of time, several major problems have existed which have prevented the widespread use of such devices.
The major problem has been the size and flexibility of the battery used to power the heating element. Batteries with sufficient power to adequately drive a heating element for a reasonable period of time have, in the past, been generally rectangular in shape and enclosed in a solid case. Thus, in a glove, for example, the battery had to be placed in the wrist portion, which made the glove uncomfortable and even dangerous when used in activities such as skiing. Also, for other items such as boots, or socks, a battery pack has been used and worn at the waist or ankle of the individual, which also resulted in a bulky and often heavy item required to be carried by the user. In addition, of course, the fact that prior batteries used as power sources were bulky, and the fact that long wiring was required between the battery and the heating element, only added to the discomfort of the user.
Chemical heaters, on the other hand, which utilize the exposure to oxygen to begin the heating cycle, are generally of relatively short duration, and once begun do not have convenient shut down.
It is, therefore, an object of the instant invention to provide a heating element for garments which eliminates the problem of a bulky power source.
It is a further object of the instant invention to provide a heating element for garments which is lightweight, inexpensive, readily replaceable and which can adapt to the contour of various body parts.
It is a still further object of this invention to provide a battery-heating element combination in which the two together perform functions of which either is incapable of independently. To wit, where the batteries provide a heat sink for the heating elements, and in which the heating element increases the efficiency of the battery.
Flexible batteries are also known in the prior art. One such battery is described, for example, in U.S. Pat. No. 3,023,259, granted to Myron A. Coler, et al on Feb. 27, 1962. This patent describes a flexible battery which may be wrapped around a person, under his or her clothing, so that body heat may be utilized to maintain the electrochemical system at an efficient operating level under low temperature conditions. The suggested use for the battery described in U.S. Pat. No. 3,023,259 is for operating transistorized radio equipment under Arctic conditions.
Another type of flexible battery is described in U.S. Pat. No. 4,092,464 granted to Arabinda N. Dey on May 30, 1978. This patent describes a high energy battery which is particularly designed to be extremely flexible and pliable without having an adverse effect on its discharge properties either during or after subjection to stress. Although no specific use is described in this patent, it is apparent that this battery could be used to conform to the shape of various body parts. Other flexible batteries are described in U.S. Pat. Nos. 4,761,352, 3,725,133 and 3,674,562.
Even though flexible batteries have been known for over thirty years, and even though it known that body heat will increase the efficiency of a battery by raising its temperature, batteries and heating elements tend to be used in the same old fashioned method where the heating element is used in the usual manner to raise the ambient temperature and the battery is connected through wires and provides a remote source of energy.